Screw thread comparator



March 11, 1952 B. w.- SWANSON 2,588,431

' SCREW THREAD COMPARATOR Filed April 28, 1948 2 SHEETS-SHEET 1 VENTOR. 5:901? 14 i swmvao/v 34 41 V BY I, I I

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March 11, 1952 B. w. SWANSON 2,588,431

SCREW THREAD COMPARATOR Filed April 28. 1948 2 SHEETS-SHEET 2 l A 7'7'OFNEK v i atented Mar. ll,

UNITED STATES PATENT OFFICE 2,588,431 U soREw THREAD COMPARATOR Bror W. Swanson, Elmwood, Gonrn, assignonby' mesne assignments, to Anthony ll Kasprow, Felix A. Kasprow, J osepln W. Kasp'row, .Stephen G. Kasprow, all of New Britain, and Meyer E. Bailey, New Haven, Conn.

Application April 28, 1948, seal nt. 23,732

4 Claim.

This invention relates to screw thread comparators and. more particularly to such com parators as are described in my co-p'ending application S. No. 578,323, filed February 16, i945 and intended for comparing or measuring threaded parts on a production basis.

An object of this invention is to provide a comparator which is particularly adapted to quickly and accurately compare threaded articles on a production basis. 4

A further object of the invention is to provide such a device which is constructed for maximum accuracy, efficiency and ease of operation.

A still further object of the invention is to provide certain novel elements of construction whereby loose fits and lost motion in the mechanism may be eliminated to increase the accuracy of the comparator.

Further objects and advantages of the invention Will be more clearly understood from the following description and from the accompanying drawings, in which- Fig. l is a plan view of a comparator embodying my invention.

Fig. 2 is a side view thereof, partially in central vertical section.

Fig. 3 is a plan view on line 33 of Fig. 2.

Fig. 4 is a front view with parts broken away and showing the comparator in its loading position.

Fig. 5 is a similar view showing the comparator in its measuring position.

I Fig. 6 is a sectional plan view on line 6-6 of Fig. 2.

Fig. '7 is an enlarged front View, partially in central vertical section, showing a portion of the operating mechanism.

Fig. 8 is a side view of the upper portion of the die support.

Fig. 9 is a similar view showing the operating lever in the die opening position.

Fig. 10 is a further enlarged fragmental plan view on the same plane as Fig. 3 but with the supporting member removed.

As shown in the drawings, my improved comparator comprises a base 5 upon which is mounted a vertical post 6 having secured thereto a conventional indicator 1 that is adjustably mounted on said post by means of a clamping bar 8 having 'a clamping screw 9 thereon.

The said indicator is provided with the usual plunger 10 for operating the pointer I l thereof to indicate the measurements of the parts being gaged or compared.

A die support i2 is pivotally mounted in the post 6 for rotation about a vertical axis so that said support may be moved into a loading position wherein it is out of register with the plunger ID to permit loading the work into the 'dies without causing excessive operation of the indicator. The said support 12 is preferably (J-shaped to provide an anvil portion is for supporting the lower portionjlil of a thread gage and a head portion 15 in which is slidably mounted a plunger l6 which carries the upper half I! of the saidthr'ead gage. The said plunger is is slidable in a bearing sleeve l8 and has an extension IB thereon, the end of which engages with the plunger 10 for operating the indicator 7. The said plunger I6 is normally urged downwardly to permit closing of the gage die halves l4 and {H by means of a spring 20 that is positioned bet-ween'the end of the plunger i6 and a cap :21 that threaded to the head l5.

The plunger 16 is operated to raised position for separating the die halves M and I! by means of a lever 22 which is pivoted to the support i2 by a pivot screw 23 and has an extension 24 thereon for operating a'stud 2'5 that is connected to the plunger 16 and projects therefrom through a slot 26 in the side of the head l5 and the sleeve "l8. H

In order to provide 'for the necessary crosswise movement of the extension 24, relatively to the direction of movement of the plunger l8, due ;to the movement of said extension around the axis of the pivot screw '23, the pin 25 1s connected to said extension by means of an eccentrio connecting disk 2-1 which is rotatably mounted in an opening 28 in the extension 24. The disk is provided with a flange engaging a shoulder in said opening for preventing the disk from sliding outwardly in the opening and the said disk is prevented from sliding inwardly by abutment with the end of the pin 25 which fits within -an oft-center recess '29 in said disk.

When the "lever 22 is rocked downwardly by means of the thumb piece 30, the extension 24 is rocked upwardly, lifting the pin 25 and thereby raising the plunger 16 against the tension of the spring 20 to open the die halves M and H. As the said pin is :moved upwardly, the slot 26 will retain it :against rotation so that its sliding movement is on a line running parallel to the axis of the plunger, while the movement of the connecting disk 27! is on an are from the axis of the pivotscrewn.

To compensate for the difference in motion between the pin and the :connecting disk, the said disk will rotate in the opening 28 and follow the pin .25, as .ic'learly illustrated in Fig. 9 of the drawings. This will prevent lost motion, such as'would result from a pin and slot connection, such as commonly used, and also provide' :a smoothness :of operation that is permitted by the rotation of the connecting disk in the opening and which is not possible in a conventional pin-and slot connection.

In order .to pivotally mount the support 52 on the post :6, the said support is provided with a shank '31 that projects into a notch 32 in the said post :andiis' pivoted in said notch by means of -balls, '3*3e*3 3. which engage tapered annular shoulders in the opposite ends of a hardened shouldered bushing 34 on the pivotal axis of the shank 3|. The said balls 33-33 are mounted in supporting rods 35-35 which have tapered shoulders in their ends for receiving the said balls 3333. These rods are slidable within a bore 36 that extends lengthwise through the post 6 and are adjustable lengthwise in said bore by means of thrust members in the form of screws 31-31 which are threaded to the walls of the recesses 38-38 in said post and which are coaxial with the bore 36, so that they will retain the said bars against the balls 3333 for pivotally mounting the support [2.

The thrust members 31-31 may be adjusted to eliminate looseness in the pivotal mounting of the support 12 and also to provide the desired amount of tension upon the bearing balls 3333 for permitting proper pivotal movement of the support without lost motion.

It will be understood that, in order to provide for maximum accuracy in the reading of the indicator 1, it is necessary that there be no lost motion in the pivotal bearing for the supporting member l2 so that, when the said member is moved into register with the indicator and the extension l9 engages the plunger II], the relation between said plungers will always be the same and the reading on the indicator will therefore be accurate.

In order to eliminate such lost motion, it is also necessary to eliminate play between the supporting rods 35-35 and the walls of the bore 36., I, therefore, provide at the bearing ends of said rods a plurality of radial slits 39 which extend for a distance from the said ends and permit the rods to expand into tight engagement with the walls of the bore 36 when endwise pressure is applied to the said rods against the bearing balls 3333 by means of the thrust members 31-31 and the said balls co-act with the tapered shoulders at the ends of the rods to expand them into tight engagement with the bore and thereby eliminate side play and lost motion which could otherwise cause objectionable vertical rocking movement of the support [2.

The balls 33 are preferably provided with stems which extend into the axial bores 40 in the rods and connect the said balls to the rods for facilitating assembly and disassembly of the comparator.

When the supporting member I 2 is mounted on the post 6, the shank 3| is first inserted in the slot 32. The rods 35-35, with the balls 3333 thereon, are then inserted through the opposite ends of the post 6 into opposite ends of the bore 36 until the balls engage the tapered surfaces on the bushing 34. The thrust members 31-31 are then threaded into position against the ends of the rods 35-35 and adjusted until the required amount of endwise thrust has been applied to force the said bearing balls into contact with the tapering surfaces of the bushing 34 with suflicient pressure to eliminate play or looseness In order to facilitate the operation of my improved gaging device, I provide a stop, preferably in the form of a post 4|, which is mounted on the base 5 in position to engage the side of the support 12 and locate the extension I9 thereof into axial alignment with the plunger ll] of the indicator.

In the operation of my improved device, the supporting member is first moved to the loading position illustrated in Fig. 4. The lever 22 is then operated to raise the upper die jaw l1 and permit insertion of the work to be gaged between the said jaw l1 and the jaw [4. Upon the said lever being released, the spring 26 will force the jaw l1 downwardly and thereby firmly engage the thread on the work piece between the die jaws l1 and I4 and locate the said piece in position to be gaged or compared. The said supporting member is then swung on its pivotal axis against the stop 4|. When in this position, the extension l9 will be in axial alignment with the plunger [0 of the indicator and it will raise the said plunger l0 slightly to rotate the pointer I l' and show on said indicator the actual measurement of the work piece contained between the jaws l4 and I1.

It will be understood that by adjusting the indicator l at the proper height on the post 6, by means of the clamping member 8 and adjusting screw 9, the plunger It] may be engaged by the extension IS on the plunger I6 and be moved endwise for the required distance to permit proper operation of the pointer II for indicating the measurement of the work piece.

When the supporting member is swung into loading position, and the jaw I1 is moved by operation of the lever 22, the extension l9 will be permitted to move upwardly with said jaw without operating the plunger [0 of the indicator. The lever 22 being released before the supporting member I2 is swung back into gaging position and against the stop 4|, the said extension will have moved downwardly so that, when it engages the plunger [0 of the indicator, the plunger will be moved only for the slight distance required to indicate a discrepancy in the size of the Work being gaged. This will eliminate excessive operation of the indicator, such as would be caused were the supporting member l2 not adapted to be swung into the loading position and the extension l9 permitted to move the plunger Ill for the full distance required to open the jaw l1 sufliciently to place the work in the die, which would result in rapidly revolving the pointer H and consequently causing excessive wear on the delicate mechanisms of the indicator.

From the above description it will be clearly understood that my invention provides a comparator or gaging device which will facilitate insertion and removal of a piece of work to be gaged without causing excessive operation of the indicator mechanism, such as would result in rapid wear on the parts of said mechanism to a point where it would give inaccurate results in gaging dimensions for the closeness generally required from such devices.

I claim:

1. In a comparator for testing the condition of threads on articles, a base, a post carried by said base, there being a transverse notch extending inwardly of said post intermediate the ends of the latter, said post being provided with a first longitudinal bore extending inwardly of the lower end thereof and terminating in said notch and a second longitudinal bore in alignment with said first bore and extending inwardly of the upper end of said post and terminating in said notch, a first rod slidably supported within said first bore, a second rod slidably supported within said second bore, each of said first and second named rods being slit adjacent the end contiguous to said notch, a ball positioned adjacent to and supported in the end of each of said rods contiguous to said notch, a support carrying coacting dies spaced vertically from each other positioned transversely of said post and having one end extending into said notch and engageable on its opposite faces thereof with said balls, and thrust means engageable with each of the other ends of said rods for positioning said rods to retain said balls in engagement with said one end of said support and said rods against lateral movement in said bores to thereby permit swinging movement of said one end support about said balls as a vertical pivot in said notch.

2. In a comparator for testing the condition of threads on articles, a base, a post carried by said base, there being a transverse notch extending inwardly of said post intermediate the ends of the latter, said post being provided with a first longitudinal bore extending inwardly of the lower end thereof and terminating in said notch and a second longitudinal bore in alignment with said first bore and extending inwardly of the upper end of said post and terminating in said notch, a first rod slidably supported within said first bore, a second rod slidably supported within said second bore, each of said first and second named rods being slit adjacent the end contiguous to said notch, a ball positioned adjacent to and supported in the end of each of said rods contiguous to said notch, a support carrying coacting dies spaced vertically from each other positioned transversely of said post and having one end extending into said notch and engageable on its opposite faces thereof with said balls, one of said dies being movable toward and away from the other of said dies, thrust means engageable with each of the other ends of said rods for positioning said rods to retain said balls in engagement with said one end of said support and said rods against lateral movement in said bores to thereby permit swinging movement of said one end of said support about said balls as a vertical pivot in said notch, gauge means spaced from and carried by said post engageable with said movable die and operable in response to movement of the latter die away from the other die, and stop means on said face and engageable with said support when the latter has been swung to a position such that said movable die is in engagement with said gauge means.

3. In a comparator for testing the condition of threads on articles, a base, a post carried by said base, there being a transverse notch extending inwardly of said post intermediate the ends of the latter, said post being provided with a first longitudinal bore extending inwardly of the lower end thereof and terminating in said notch and a second longitudinal bore in alignment with said first bore and extending inwardly of the upper end of said post and terminating in said notch, a first rod slidably supported within said first bore, a second rod slidably supported within said second bore, each of said first and second named rods being provided with a plurality of spaced radial slits extending inwardly longitudinally from the end contiguous to said notch and terminating at a point spaced from the latter end, a ball positioned adjacent to and supported in the end of each of said rods contiguous to said notch, a support carrying coacting dies spaced vertically from each other positioned transversely of said post and having one end extending into said notch and engageable on its opposite faces thereof with said balls, and thrust means engageable with each of the other ends of said rods for positioning said rods to retain said balls in engagement with said one end of said support and said rods against lateral movement in said bores to thereby permit swinging movement of said one end support about said balls as a vertical pivot in said notch.

4. In a comparator for testing the condition of threads on articles, a base, a post carried by said base, there being a transverse notch extending inwardly of said post intermediate the ends of the latter, said post being provided with a first longitudinal bore extending inwardly of the lower end thereof and terminating in said notch and a second longitudinal bore in alignment with said first bore and extending inwardly of the upper end of said post and terminating in said notch, a first rod slidably supported within said first bore, a second rod slidably supported within said second bore, each of said first and second named rods being provided with a plurality of spaced radial slits extending inwardly longitudinally from the end contiguous to said notch and terminating at a point spaced from the latter end, a ball positioned adjacent to and supported in the end of each of said rods contiguous to said notch, a sup-port carrying coacting dies spaced vertically from each other positioned transversely of said post and having one end extending into said notch and engageable on its opposite faces thereof with said balls, one of said dies being movable toward and away from the other of said dies, thrust means engageable with each of the other ends of said rods for positioning said rods to retain said balls in engagement with said one end of said support and said rods against lateral movement in said bores to thereby permit swinging movement of said one end of said support about said balls as a vertical pivot in said notch, gauge means spaced from and carried by said post engageable with said movable die and operable in response to movement of the latter die away from the other die, and stop means on said base and engageable with said support when the latter has been swung to a position such that said movable die is in engagement with said auge means.

BROR W. SWANSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 45,639 Rollins Dec. 27, 1864 576,474 Sampson Feb. 2, 1897 1,625,462 Frauenthal Apr. 19, 1927 1,808,816 Johnson June 9, 1931 1,862,146 Hoke June 7, 1932 2,024,020 Aldeborgh Dec. 10, 1935 2,073,089 Autenreith Mar. 9, 1937 2,363,077 Moore Nov. 21, 1944 2,371,451 Larson Mar. 18, 1945 2,425,381 Lovick Aug. 12, 1947 2,431,021 Bourdelais Nov. 18, 1947 

